Creating a Prior Month Indicator Column - that works year over year

Hey DJBAJG ,

this DAX statement shows how to create a running month index column:

calendar = 
var dateStart = DATE( 2022 , 1 , 1 )
 var dateEnd = DATE( 2023 , 12, 31 )
 return

 ADDCOLUMNS(
    CALENDAR(
        dateStart
        , dateEnd
    )
    , "runningMonthIndexCalendar"
        , var YearsNoOf = YEAR( [Date] ) - YEAR( dateStart )
        var MonthNoOf = MONTH( [Date] )
        return
        YearsNoOf * 12 + MonthNoOf
 )
        

Here is a screenshot that shows that the index is incremented from December 2022 to January 2023.

Using this index will help to get the previous month's name or will help to shift dates by months for more sophisticated date-related calculations.

This adds a column to the calendar table that holds the prev month name:

, "Year Month (prev)"
            , var eomprev = EOMONTH( [Date] , -1 )
            return
            FORMAT( eomprev , "YYYY MMM" )

Another screenshot:

Regards,
Tom